It is known to provide vehicles with hydrostatic transmissions having an input control shaft which is pivoted in a first direction to propel the vehicle forward, and which is pivoted in the other direction for driving the vehicle in the reverse direction. Vehicles with hydrostatic transmissions include a control mechanism or linkage structure operatively connected to the input control shaft for allowing an operator of the vehicle to control the operation of the transmission. These control linkages typically include a hand lever or foot pedals engagable by the operator during vehicle travel. These linkages typically include a neutral return feature which pivots the input control shaft back to its neutral position when the operator releases the hand lever or foot pedal. Many such neutral return linkages are relatively complex and include a relatively large number of parts. Some conventional neutral return linkages are adjustable for allowing the operator to adjust the linkage to return the hydrostatic transmission to a precise neutral mode such that the vehicle will not creep in the forward or reverse direction when the linkage is in its neutral mode. This adjustment feature tends to add complexity to the linkage and can add a high number of parts of the overall structure.
It is also known to provide a neutral start feature on vehicles having hydrostatic transmissions. Neutral start mechanisms are designed to prevent the vehicle power source or engine from being started while the transmission is in a driving, non-neutral mode, and thereby generally prevent the vehicle from lunging forward when started. Conventional neutral start mechanisms tend to add complexity to the overall linkage structure and contribute to a relatively high overall part count for the linkage structure.
Therefore it would be desirable to provide a control linkage mechanism for a hydrostatic transmission which returns the transmission to a neutral mode when the operator releases the control, which is simple in construction and operation, and has a relatively low part count. It would be desirable for such a mechanism to be adjustable for insuring that the hydrostatic transmission is returned to its precise neutral, non-driving mode by the linkage when the operator controls are disengaged. It would be desirable to provide such a mechanism with a neutral start feature which prevents the operator from starting the vehicle when the transmission is in any mode other than its neutral mode. It would be desirable for such a neutral start mechanism to be relatively simple in construction, having relatively few pads, and having a relatively low cost of manufacture and assembly.